Protein kinase inhibition in G2 causes mammalian Mcm proteins to reassociate with chromatin and restores ability to replicate.
Intact nuclei from G2-phase mammalian cells will replicate their DNA in Xenopus egg extract if they are preexposed to the protein kinase inhibitor 6-dimethylaminopurine in vivo (Coverley et al., Exp. Cell Res. 225, 294-300, 1996). Here, we demonstrate that this competence to rereplicate is accompanied by alterations in the subcellular distribution of the Mcm family of proteins, which are implicated in replication licensing (Hennessy et al., Genes Dev. 4, 2252-2263, 1990; Kubota et al., Cell 81, 601-609, 1995; and Chong et al., Nature 375, 418-421, 1995). All family members reassociate with chromatin in G2 cells and this correlates closely with regeneration of replication competence. Moreover, newly bound Mcm proteins are functional for replication because, unlike untreated G2 nuclei, replication of treated G2 nuclei in vitro occurs independent of the Xenopus Mcm protein complex. These observations show that the postreplicative state is actively maintained in G2 cells by a protein kinase(s) which regulates the behavior of Mcm family proteins.
Coverley
D
D
Department of Zoology, University of Cambridge, United Kingdom.
Wilkinson
H R
HR
Madine
M A
MA
Mills
A D
AD
Laskey
R A
RA
D000225:Adenine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D002453:Cell Cycle / Q000502:physiology; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002467:Cell Nucleus / Q000187:drug effects / Q000502:physiology*; D002843:Chromatin / Q000378:metabolism*; D004261:DNA Replication; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016195:G2 Phase / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D008322:Mammals; D064126:Minichromosome Maintenance Complex Component 3; D009687:Nuclear Proteins; D009865:Oocytes / Q000502:physiology; D047428:Protein Kinase Inhibitors; D014020:Tissue Extracts; D014982:Xenopus laevis
D018797:Cell Cycle Proteins; D002843:Chromatin; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; C066470:MCM3 protein, human; D009687:Nuclear Proteins; D047428:Protein Kinase Inhibitors; D014020:Tissue Extracts; C001020:N(6),N(6)-dimethyladenine; D064126:Minichromosome Maintenance Complex Component 3; D000225:Adenine